N.Osborne K.Verhaegh M.D.Bowden T.Wijkamp N.Lonigro P.Ryan E.Pawelec B.Lipschultz V.Soukhanovskii T.Biggelaar
High resolution D2 Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and elongated conventional divertor density ramps with D2 fuelling from the mid-plane high-field side. In the Super-X case (density ramp from Greenwald fraction 0.12 to 0.24), the upper divertor showed ground state rotational tempe…
PreprintK. Verhaegh B. Lipschultz J.R. Harrison F. Federici D. Moulton N. Lonigro M. O'Mullane N. Osborne P. Ryan T. Wijkamp B. Kool C. Theiler A. Thornton
First quantitative analysis of the detachment processes in the MAST Upgrade Super-X divertor show an unprecedented impact of plasma-molecular interactions involving molecular ions, resulting in strong ion sinks, leading to a reduction of ion target flux. This starts to occur as the ionisation source detaches from the target, leading to a build-up o…
PreprintK. Verhaegh A.C. Williams D. Moulton B. Lipschultz B.P. Duval O. Février A. Fil J. R. Harrison N. Osborne H. Reimerdes C. Theiler
Divertor detachment requires plasma-neutral interactions which dissipate momentum, power and particles simultaneously. Plasma-molecular interactions can result in molecular ions which react with the plasma. This can contribute to detachment through molecular activated recombination (MAR) and molecular activated dissociation (MAD), both of which cre…
Preprint PublishedK. Verhaegh B. Lipschultz J.R. Harrison N. Osborne A. Williams P Ryan J. Allcock J. Clark F. Federici B. Kool T. Wijkamp A. Fil D. Moulton O. Myatra A. Thornton T.O.S.J. Bosman C. Bowman B. Duval S. Henderson R. Scannell the MAST Upgrade team the EuroFusion MST1 team
In this paper we a first qualitative analysis of the atomic and molecular processes at play during detachment in the MAST-U Super-X divertor, using divertor spectroscopy data. Our analysis indicates a wide operational regime of detachment of the MAST-U super-X divertor, which can be roughly separated in four phases: 1) The ionisation front detac…
PreprintM. Knolker T. Osborne E. Belli S. Henderson A. Kirk L. Kogan S. Saarelma P. B. Snyder
In preparation for the upcoming MAST-U campaign, pedestal stability of spherical tokamaks is revisited by investigating standard H-mode discharges on MAST. As a step beyond previous studies, both ion and electron profiles are used for obtaining equilibria and a diverse set of pedestals is evaluated. Stability analysis with the ELITE and CGYRO codes…
Preprint PublishedZ. Yan G.R. Mckee R.J. Groebner P.B. Snyder T.H. Osborne M.N. Beurskens K.H. Burrell
Detailed 2D measurements of long-wavelength density fluctuations in the pedestal region with beam emission spectroscopy during the period between edge localized modes (ELMs) indicate two distinct bands of fluctuations propagating in opposite poloidal directions in the plasma frame: one lower frequency band (50–150 kHz) advects in the ion-diamagne…
PublishedR. Scannell M. Beurskens P.G. Carolan A. Kirk M. Walsh T. O’Gorman T.H. Osborne
Deconvolution of Thomson scattering (TS) profiles is required when the gradient length of the electron temperature ( T e ) or density ( n e ) are comparable to the instrument function length ( R ). The most correct method for deconvolution to obtain underlying T e and n e profiles is by consideration of scattered signals. However, deconvolution at …
Published